Human Health and Controlled Waters Risk Assessment Natural Gas Refining Facility, UK

OIL & GAS

Ref: PS0024b

Project Summary Human Health and Controlled Waters Risk Assessment Natural Gas Refining Facility, UK

Key Project Elements

• Review of Site Soil and Groundwater Data

• Desktop Study of Hydrogeology

• Preparation of a Conceptual Site Model

• Identification of Potential Pollutant Linkages

• Human Health GQRA

• Controlled Waters DQRA

CRA is providing a range of consultancy services to a gas refining installation in the UK, including on-going groundwater monitoring in support of the conditions of the installation’s Environmental Permit. The collection of groundwater data identified that a potential groundwater contamination source was present beneath the installation, requiring an assessment of the potential risk to the environment. CRA undertook a review of the following information to form the basis of a Conceptual Site Model (CSM) for the installation: • Soil and groundwater analytical data obtained for the installation

between 1989 and 2010 to identify potential contamination sources, and a review of site processes to identify contaminants of concern; and

• Geological, hydrogeological and hydrological literature information and site geological data obtained from previous investigations to identify potential contamination pathways and receptors.

The CSM highlighted potential pollutant linkages relating to human health (risk posed by soil and volatile vapours) and controlled waters (principal aquifer, groundwater abstraction points and surface water features). CRA undertook a Generic Quantitative Risk Assessment (GQRA) to assess the risk to human health from soil contamination, using published Generic Assessment Criteria (GAC) and undertook a Detailed Quantitative Risk Assessment (DQRA) to assess the risk to controlled waters, using the Environment Agency approved ConSim software. A qualitative assessment of vapour intrusion was also undertaken. The risk assessment process allowed CRA to eliminate pollutant linkages that were unlikely to pose a risk to the environment and to identify those that may pose an unacceptable risk, thus refining the CSM. CRA then produced recommendations for further works required to address and mitigate the potential risks for the currently operating site. Throughout the project CRA worked closely with the client to provide regulatory support and environmental advice, which is currently on-going.